ptp_clock: future-proofing drivers against PTP subsystem becoming optional
Drivers must be ready to accept NULL from ptp_clock_register() if the
PTP clock subsystem is configured out.
This patch documents that and ensures that all drivers cope well
with a NULL return.
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Eugenia Emantayev <eugenia@mellanox.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Acked-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/ptp_clock_kernel.h b/include/linux/ptp_clock_kernel.h
index 6b15e16..5ad54fc 100644
--- a/include/linux/ptp_clock_kernel.h
+++ b/include/linux/ptp_clock_kernel.h
@@ -127,6 +127,11 @@
*
* @info: Structure describing the new clock.
* @parent: Pointer to the parent device of the new clock.
+ *
+ * Returns a valid pointer on success or PTR_ERR on failure. If PHC
+ * support is missing at the configuration level, this function
+ * returns NULL, and drivers are expected to gracefully handle that
+ * case separately.
*/
extern struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,